Broadly used as a coordinates input device for various types of electronic equipment including a tablet terminal, a smartphone and the like is a so-called “touch panel type coordinates input device” (hereinafter referred to as “a touch panel”), which enables an input to be made with a finger or a touch stylus pen touching (contacting) a display screen.
There are some touch panel type input devices based on capacitive sensing, resistivity variations and the like known in the art (see Patent Literature 1 and 2 as stated below), all of which principally have a sensor capable of detecting a touched coordinate position incorporated typically in the display itself.
One of the problems with this type of touch panel input devices includes that they do not allow the touch panel functionality to be added in a retrofit manner to a screen with no such touch panel functionality provided originally, such as, a monitor screen having only a displaying functionality, and a screen projected by using a projector and the like.
A method using an oscillating stylus pen has been proposed, which can work as well with the display panel equipped with no such special input functionality in the display itself, wherein the coordinates being input may be determined by a detected oscillation. This method allows for the computation of the input position by touching the panel with an input stylus pen having an oscillator that oscillates at a specific frequency; and computing an arrival time from a driving signal of the oscillator of the stylus pen and a detected waveform from an oscillation detector in synch with the oscillator so as to compute the input position.